The pullout test is perhaps the most reliable technique to estimate the in situ compressive strength of concrete. In this study, a new pullout test was conducted to evaluate high strength concrete through a wall specimen and concrete compressive cylinders. It found that the correlation curve, concrete compressive strength versus pullout force, is linear and useful to predict concrete strength.

The in-depth inspection and maintenance process is based on the ‘Special Act on the Safety Control of Public Structures’ and accompanied specific guide. They prescribe the evaluation standard for physical condition and safety on structures. Recently we are faced with the threat coming from the aging of structures and external condition such as climate change. In this study, sustainable and long-term maintenance strategy is derived.

A dynamic displacement estimation system is developed by integrating laser Doppler vibromter (LDV) and light detection and ranging (LiDAR). The system includes hardware level integration for simultaneous measurement of two devices and data fusion of two measurement signals based on Kalman filter smoothing algorithms. For hardware integration of two devices, the laser beam directions and the triggering of measurement of LDV and LiDAR are controlled on the level of built-in commands of the devices. The distance data sequentially measured by LiDAR is converted to dynamic displacement of high noise and low sampling rate, and fused with the velocity measured by LDV which has high sampling rate and low noise but accumulated bias error when integrated. Using the Kalman filter based data fusion algorithm, it is able to estimate dynamic displacement in which the drawbacks of two devices are effectively removed. The proposed system is applied to a dynamic loading test on a highway bridge and the performance is verified.

In this paper, it proceed the fascinating experimental study to use the system identification(SI) for a long time measurement. The aim of the study is to identify the dynamic characteristics using the SI based on ambient vibration(AV) tests for monitoring systems at building structures. White noise, which is naturally occurring for harmonic components, and free vibration tests are employed in obtaining output data. A definite answer of the dynamic characteristics manages to extract from the frequency domain decomposition(FDD) method under the condition of the white noise. The singular value of the following test is used by FDD. These results show the validity of AV test and the usability of FDD in comparison with two tests. The result of the study is to design practical criteria for SI for building structures based on AV tests.

All living organisms use memory and oblivion algorithms considering the estimated lifetime and the changes in the ambient environment. Because of the expected lifetime of a bridge is similar to the human’s one, if a bridge uses the same algorithm of human memory, the abnormal responses of the structure can be easily detected. This paper introduces unfamiliarity index (UFI) that calculated from the FFT results of the short term timeline acceleration responses. If this algorithm, which can detect an abnormal behavior from the maximum constant signal, is used to the terminal sensors of an structure, more accurate safety control criteria will be prepared efficiently.

This large diameter cable NDE technique was based on the direct current (DC) magnetization technique and a search coil-based magnetic flux measurement. A total flux sensor head was fabricated that was consisted by a magnetization part to magnetize the specimen and a sensing part to measure the total magnetic flux. The magnetization part was consisted by an electro-magnet yoke that fabricated by winding a coil. The magnetic field for magnetizing the main cable was generated by applying the low frequency DC voltage to the winded coil. The sensing part was configured by two semi-circular search coils, and it measures the electromotive force that pass through the search coil by using the faraday’s law of induction. Total flux was calculated by integrating the measured magnetic flux. Then, B-H curve was extracted using the total flux, and cross-sectional loss can be detected using variation of features from the B-H curve.

This study proposes a FE model updating strategy based on data fusion of acceleration and angular velocity. The use of acceleration and angular velocity gives richer information than the sole use of acceleration, allowing the enhanced performance particularly in determining the boundary conditions. A numerical simulation is presented to demonstrate the proposed FE model updating approach using the data fusion.

Shows the problem of exposure to vibration generated from vehicle and train adjacent to the railway facilities are housing facilities. As a method for solving the problems caused by the vibration countermeasures have been provided various methods such as the vibration of the vibration trajectory, wave barriers wall, vibration isolation mat. Therefore, in the present study is to evaluate the vibration analysis by using vibration isolation mat for vibration reduction of housing facilities.

The purpose of this study is model development of displacement estimation of simple beam receiving the concentrated load using terrestrial LiDAR. Using the terrestrial LiDAR it is possible to supplement touch sensor’s disadvantages which have the limit to the displacement measurement. The data which is obtained by terrestrial LiDAR goes through coordinate transformation and dividing elements. And then, applying the Cubic Smoothing Spline Interpolation(CSSI) we will find the optimal value for displacement estimation. Also, based on the assumed displacement it is possible to estimate the stress distribution shape of the experiment model.

This study examined the collapse of bridge under extreme events. As a result, numerous bridges collapsed by scour, collision, fire and earthquake. The research team studied four cases of previous bridge collapse and restoration following extreme events. Finally, the disaster type factor were selected.

In prestressed concrete (PSC) which is adopted in a wide variety of civil engineering structures, including bridges and nuclear power plants bridges, structural damage such as concrete cracks is related to the shift of the neutral axis due to the loss of tendon forces. As such, monitoring the tendon force is important to maintain PSC bridges and prolong its remaining life. However, measuring the tendon force of PSC bridges in service is challenging. The direct measurement using load cells is often impractical for in-service PSC bridges; indirect estimation approaches using vibration responses are developed as alternatives to the direct measurement. The vibration-based approaches typically use modal properties such as natural frequencies; however, the fact that the frequency change due to the prestress force is generally insignificant compared to temperature effects has degraded the applicability of the vibration-based methods to the real world problems. This study proposes a multimetric data fusion algorithm using acceleration and strain measurements to monitor the prestress force change. Laboratory-scale testing using a 6 meter simply supported prestressed concrete beam is conducted to verify the efficacy of the proposed approach using the data fusion.

In this study an algorithm estimating total load and axial load was conducted using BWIM(Bridge Weigh-in-Motion) system with precision analysis model. Driving test for running vehicle is necessary but it needs much cost, time, and especially hard to applicate to various driving condition. Thus we need a numerical-simulation method for resolving the cost and time problems of driving test for vehicle, and a way to measure bridge responses reflecting many unpredictable situations. Using a precision analysis model reflecting the dynamic characteristic contributes to increase the accuracy in numerical simulation. In this paper, we conduct a numerical simulation to apply a precision analysis model, which reflects the dynamic characteristic of a bridge using the Bridge Weigh-in-Motion system, and suggested a method of overloaded vehicle enforcement technology using the precision analysis model.

Through Estimation of stress distribution, both value and location of the maximum stress can be found. and the maximum stress is very important indicator for structural safety evaluation. In this connection, a lot of studies to estimate stress distributions are conducted. But studies on the optimal number and location of measurement points are few. So, In this study, the effects of the number and location of measurement points on the estimation stress distribution for the steel beam structure using motion capture system and cubic smoothing spline interpolation are researched.

The maintenance of the general structures has been studied until today. but maintenance guide line of the wind power tower has not been studied yet. In this study it was performed analysis on structural features through wind power tower technique data survey. which can be developed to basic data for the wind power tower maintenance manual through analysis of vulnerable elements.

일반적으로 토목 구조물의 피로분석 결과를 향상시키기 위해서는 교량 각 절점에서의 정교한 수치모델 또는 변형률 측정값이 필요하지만 실재하는 토목 구조물의 정교한 수치모델을 만드는 것은 쉽지 않으므로 두가지 모두 쉬운일은 아니다. 또한 구조물의 전 지점에서 시간에 따른 측정 데이터를 계측하는 것 또한 불가능하다. 그래서 본 연구에서는 칼만필터를 이용하여 측정되지 않은 위치에서의 변형률 계측값을 추정하고자 한다. 해양 토목구조물의 인풋을 평균이 0인 BLWN(band limited white noise)으로 가정할 수 없으므로 평균이 0이 아닌 인풋을 사용하였고, 변형률 추정에 데이터 융합의 효과를 확인하기 위해 멀티센서 데이터 융합 기법을 사용하였다.

The LH seismic system is composed of structure, brace, and LH damper designed high damping rubber. The dynamic test with shaking table was performed to analyze the vibration characteristic of the RC Frame and LH seismic system.

SHM에서 변위는 구조물의 동적 특성을 파악하는 핵심정보다. 이를 구조물과 직접 접촉하여 자기장 변화를 전기적신호(LVDT), 직접적으로 측정하는 방안으로 LVDT, GPS, LDV Displacement is one of the most fundamental responses, containing useful information regarding dynamic behavior of a structure. Traditional displacement measurement devices such as LVDT have disadvantages in its high-cost and few options on installation place. For the sake of economic reason, vision-based displacement measurement systems using low-cost cameras have been developed, yet these approaches still have difficulties in finding appropriate camera positions; camera should be placed perpendicular to targets. This study presents a new vision-based displacement measurement system using the planar homography method that gives accurate displacement, allowing the camera to have an arbitrary angle toward target. The vision-based system is experimentally verified using a low-cost camera and a target with four circles.

Currently, global warming problem is serious. One of reasons of global warming is CO2 emissions. As an alternative means to prevent this, there is an environment-friendly effect of modular bridge method. After analyzing the CO2 emissions of the steel modular bridge which is used in a modular bridge based on D/B W.B.S analysis program and by comparing the CO2 emissions with that of the similar type of bridge, it is intended to analyze the environmental-friendly of modular bridge through the evaluation of the CO2 emissions of modular steel girder bridge of 21m.

This paper aims at featuring dynamic characteristic of 2-span bridge by means of an cochlea-inspired artificial filter bank(CAFB), for the purpose of effective acquirement of real-time valid dynamic(acceleration) responses. Through dynamic testings performed on a model of 2-span bridge, its dynamic characteristics were featured on natural frequency. They were evaluated in comparison to wired measurement responses. Finally, the dynamic wireless measurement system on the basis of CAFB were found technologically and economically effective by obtaining valid dynamic(acceleration) responses whose size was compressed over the frequency range of interest.

Since more than 70% of our country is made of mountains, a lot of underground facilities and tunnels are used for efficient use of limited land space. Recently, Shield TBM method has been used a lot since 1980. In this paper, we selected add factors for Damage factors of shield TBM method. And we analyzed weighting factors using AHP method.